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MA: Fachverband Magnetismus

MA 33: Bio- Molecular Magnetism

MA 33.9: Vortrag

Donnerstag, 26. März 2009, 12:15–12:30, HSZ 103

Effects of the Ligand Shell on the Single-Molecule Magnet Behavior in Co₅ Clusters — •J. Nehrkorn¹, O. Waldmann¹, F. Klöwer², Y. H. Lan², and A. K. Powell² — ¹Physikalisches Institut, Universität Freiburg, D-79104 Freiburg, Germany — ²Institut für Anorganische Chemie, Universität Karlsruhe, D-76128 Karlsruhe, Germany

Enhancing single-molecule magnet (SMM) behavior in molecular nanomagnets to higher temperatures is one of the great aims in this field. Incorporating Co^II ions, because of their high magnetic anisotropy, has recently attracted much interest. In this work we study three Co₅ clusters which exhibit similar cores, but differ in their coordination spheres due to the use of different ligands. Our dc and ac magnetic data revealed that one compound is clearly a SMM, one is a weak SMM, and the third one is no SMM. We interpret the data on the basis of an effective-spin Hamiltonian, which reproduces the magnetic data well and allows us to understand the trend of SMM behavior. A subtle effect of highly anisotropic systems was observed: anisotropic ferromagnetic couplings together with highly anisotropic g matrices can yield susceptibility curves with a temperature dependence usually associated to antiferromagnetic interactions.